Attitude compensated predetermined torque release wrench



Aug. 18, 1959 F. w. LIVERMONT ATTITUDE COMPENSATED PREDETERMINED TORQUE RELEASE WRENCH Filed Oct. 21, 1957 2 Sheets-Sheet 1 zbnalfflwfldz I NVEN TOR. FflA/Z [a A/I EQMOA T arrae/va s g 18, 1959 F. w. LIVERMONT ,8

ATTITUDE COMPENSATED PREDETERMINED TORQUE RELEASE WRENCH Filed on. 21, 1957 2 Sheets-Sheet 2 United ATTITUDE COMPENSATED PREDETERMINED TORQUE RELEASE WRENCH 4 Claims. (Cl. 8152.4)

This invention relates to torque-indicating wrenches which produce a signal when torque applied by the wrench reaches a predetermined value. This application relates to improvements over the adjustable torque wrench shown in my Patent 2,732,747 granted January 31, 1956.

Torque wrenches of the type disclosed in said patent give excellent performance and are accurate in service so long as the operating position of the wrench is not substantially changed. However, such torque wrenches may not produce uniform results in the following illustrated examples:

(a) One value of torque is produced when the operator or mechanic pushes down on the handle.

(b) Another value is applied when the operator pulls up on the handle.

A third value is applied when the operator swings the wrench in a horizontal plane, either pulling it toward him or pushing it away from him.

The reason for this variation in applied torque is the influence of gravity on the mass of the lever which carries the work-engaging element. In a particular commercial form of the invention, it was found that the weight of the lever influenced the torque resisting mechanism to the ex tent of about 35 inch pounds so that in the three illustrations above a torque value 35 inch pounds too high was applied in example (a), 35 inch pounds too low in example (b) and the correct value without variation in illustration (0).

The principal object of the present invention is to eliminate this variation which arises from changes in the angular position of the torque wrench and to provide a torque wrench which automatically compensates for the particular angular attitude which is employed. Another object of this invention is to provide a device of this type in which the attitude compensation is achieved by a two-part balanced lever construction. Other and more detailed objects and advantages will appear hereinafter.

In the drawings:

Figure l is a plan view partly in section showing a preferred form of my invention.

Figure 2A is a similar view on an enlarged scale showing the forward portion of the wrench assembly.

Figure 2B is a sectional view constituting a continuation of Figure 2A showing the rearward portion of the wrench assembly.

Figure 3 is a sectional elevation taken substantially on the lines 33 as shown in Figure 2A.

Figure 4 is a bottom plan view partly in section. taken substantially on the lines 44 as shown in Figure 2B.

Referring to the drawings, the adjustable torque wrench generally designated 19, includes a case or housing 11 having a first lever element 12 pivotally mounted on pin 13. The housing 11 has an open end 14 through which a portion of the lever element 12 projects. A work-engaging member 15 is mounted on the projecting portion of the lever element 12. A second lever element 16 is mounted on pivot pin 17 for swinging movement within the case 11. Interengaging parts are provided on the lever elements 12 tes Patent 0 2,899,854 Patented Aug. 18, .9

and 16 so that they turn about their parallel pivot pins 13 and 17 in opposite directions. As shown in the drawings, these cooperating parts include a projection 18 on the forward end of the lever element 16 received within a recess 19 provided on the rearward end of the lever element 12. As best shown in Figure 2A, the projection 18 is pivoted with opposed rounded convex surfaces 20 which engage parallel faces 21 defining the sides of the recess 19. Each of the lever elements 12 and 16 is provided with a plurality of balls 22 which are mounted in sockets 23 which roll on parallel plane surfaces 24 and 25 provided within the interior of the housing 11.

As shown in Figures 2B and 4 the rearward end of the lever element 16 extends into a shell 26 which is provided on the forward end of the sleeve 27. Shell 26 is fixed as by welding 28 to the forward end of the tubular element 29. This element 29 is fixed within the case 11. A slide block 30 is mounted within the sleeve 27' and shell 26. A toggle link 31 is interposed between the rearward end of the lever element 16 and the forward end of the slide block 30. This toggle link 31 engages pivot pin 32 carried on the lever element 16 and pivot pin 33 carried on the slide block 30. The slide block 30 is provided with a roller 34 which engages a flat surface 35 provided within the shell 26.

A helical compression spring 37 is mounted within the sleeve 27 and engages the slide block at 38. The spring rests against the shoulder 39 on the non-rotary collar 40 which is also mounted within the sleeve 27 A radial pin 41 on the collar 40 travels in an axial slot 42 provided in the sleeve 27.

A load screw 43 having external threads 44 engages internal threads 45 provided on the sleeve 27. This load screw 43 is connected by inter-engaging threads 44a with the handle 46 which extends axially of the housing or case 11. The handle 46 is 'rotatably mounted with respect to the case 11 and sleeve 27. The load screw turns as a unit with the handle 46. Accordingly, rotation of the handle 46 causes the load screw 43 to travel axially with respect to the sleeve 27 along the interengaging threads 44 and 45.

Means are provided to lock the adjusting screw 43 in any selected position, and as shown in the drawings this means includes a clamping bolt 47 which is received within internal threads 48 provided on the load screw 43. A collar 49 fixed to the clamping bolt 47 engages the shoulder 39 on the collar 40 and the bolt head 50 is engageable with the shoulder 51. An annular dimple plate 52 is interposed between the load screw 43 and the non-rotary collar 40. The collar 49 and the dimple plate 52 are each provided with a series of circumferentially spaced indentations or dimples which receive balls 53.

When the clamping bolt 47 is turned to move it away from engagement with the shoulder 51, the balls 53 are locked in the indentations formed on the collar 40 and dimple plate 52 and this prevents relative turning movement between the load screw 43 and the sleeve 27. When the clamping bolt 47 is turned in the other direction to bring the bolt head 50 into engagementwith. the stop shoulder 51, the collar 49 moves away from the non rotary collar 40 to permit relative axial movement between the dimple plate 52' and the collar 40. Turning of the handle 46 relative to the case 11 and sleeve 27 causes the collar 40 to move axially as the balls 53 move into and out of the series of indentations on the dimple plate 52 and collar 40, as the load screw 43 advances along the threads 45 of the sleeve 27. When the handle 46 has been turned to the desired position to load the spring 37, the clamping bolt 47 is turned to clamp the collar 40 and dimple plate 52 against axial separation,

thereby preventing further turning movement of the handle 46 with respect to the case 11.

Turning of the clamping bolt 47 is accomplished by means of a hexagonal lock shaft 54 engaging a hollow hexagonal recess in the head 50 of the clamping bolt and also engaging the hexagonal recess within the locking knob 55. A portion of this locking knob extends beyond the end of the handle 46 for manual operation and is held in place by means of retainer ring 56.

In operation, the locking knob 55 is turned in a direction to release the clamping bolt 47 and the handle 46 is then turned relative to the case 11 to load the spring 37 to the desired extent. The knob 55 is then turned in a direction to cause the clamping bolt 47 to prevent further relative motion between the load screw 43 and the sleeve 27. The work engaging member 15 is then connected with a torque receiving part (not shown) and torque is applied manually to the wrench 10. When the applied torque reaches a predetermined value the toggle link 31 swings in a counterclockwise direction as viewed in Figure 2B around the pivot pin 33 thereby forcing the slide block 30 to move to the right against the force of the spring 37. The releasing action of the toggle link 31 occurs in a very short are of travel of the wrench and is accompanied by an audible sound and by an abrupt decrease in resistance to torque, thus signalling that rated torque has been applied to the member 15.

The positions of the pivot pins 13 and 17 are so chosen with respect to the lengths and masses of the lever elements 12 and 16 that gravity has substantially no effect on actuation of the toggle link 31. Thus, when the wrench 10 is in a horizontal position with the axis of the pivot pins 13 and 17 in a horizontal plane, the weights of the lever elements are balanced so that they tend to rotate neither clockwise nor counterclockwise. Accordingly, the desired torque value is applied to the member whether the mechanic or operator pulls upward or pushes downward on the handle.

Having fully described my invention, it is to be understood that I do not wish to be limited to the details set forth herein, but my invention is of the full scope of the appended claims.

I claim:

1. In an adjustable predetermined torque release wrench, the combination of: an elongated housing; a first lever element pivotally mounted in the forward part of the housing and supporting at its free end a workengaging, torque-transmitting member; a second lever element pivotally mounted in the housing in tandem relation to the first lever element; interengaging projections on adjacent ends of said lever elements, which cause them to turn in opposite directions about their respective pivotal mountings; resilient bias means for the lever elements disposed rearwardly of the second lever element in the handle end of the housing; a slidable link member positioned between the rear end of the second lever element and the forward end of the resilient bias means; and toggle means interconnecting the rear end of the second lever element and the forward end of the link member.

2. In an adjustable predetermined torque release wrench, the combination of: an elongated housing; a first lever element pivotally mounted in the forward part of the housing and including a relatively short lever arm supporting at its free end a work-engaging, torquetransmitting member and a relatively long lever arm; a second lever element pivotally mounted in the housing in tandem relation to the first lever element, and including a short lever arm confronting the end of the long lever arm of the first lever element and a long lever arm extending toward the end of the housing remote from the work-engaging member; interengaging projections on the confronting ends of said lever arms which cause said lever elements to turn in opposite directions about their re spective pivotal mountings, the relative mass of said lever arms being such that said lever elements are in substantial balanced condition relative to their respective axes irrespective of the position assumed by said housing; resilient bias means for the lever elements disposed rearwardly of the second lever element in the handle end of the housing, a slidable link member positioned between the rear end of the second lever element and the forward end of the resilient bias means, and toggle means interconnecting the rear end of the second lever element and the forward end of the link member.

3. In an adjustable predetermined torque release wrench, the combination of an elongated housing; a first lever element pivotally mounted in the forward part of the housing and including a relatively short lever arm supporting at its free end a work-engaging, torque-transmitting member and a relatively long lever arm; a second lever element pivotally mounted in the housing in tandem relation to the first lever element, and including a short lever arm confronting the end of the long lever arm of the first lever element and a long lever arm extending toward the end of the housing remote from the workengaging member; interengaging projections on the confronting ends of said lever arms which cause said lever elements to turn in opposite directions about their respective pivotal mountings, the relative mass of said lever arms being such that said lever elements are in substantial balanced condition relative to their respective axes irrespective of the position assumed by said housing; and means operated by movement of the extended end of the long lever arm of said second lever for measuring torque applied to said work-engaging, torque-transmitting member.

4. An adjustable predetermined torque release wrench, comprising: a pair of lever elements disposed in tandem relation and having interengaging means at their confronting ends to cause said lever elements to pivot in opposite directions; an elongated housing pivotally supporting said lever elements intermediate their respective ends, the relative mass and lengths of the arms of said lever elements being so proportioned that said lever elements maintain a balanced condition irrespective of the position of said housing; a work-engaging, torque-transmitting device at the remote end of one of said lever elements; and a means at the remote end of the other lever element tending to restrain said levers until a predetermined torque is applied on said device.

References Cited in the file of this patent UNITED STATES PATENTS 2,667,800 Garwood Feb. 2, 1954 2,732,747 Livermont Jan. 31, 1956 2,743,638 Woods May 1, 1956 2,791,141 Johnson et al May 7, 1957 2,792,733 Walraven et al. May 21, 1957 

